The effects of genetic diversity on community assembly and adaptation in Daphnia populations

Daphnia pulex populations in southwest Michigan naturally display a high degree of genetic diversity. The level of genetic diversity in D. pulex populations may influence their ecological relationships with other species. It may also influence their ability to adapt to environmental change. The ability of a population to undergo rapid adaptation to local conditions depends on available sources of phenotypic diversity. We used mesocosm experiments and surveys of natural populations to discern: (1) the degree to which natural populations are undergoing selection on quantitative traits, (2) the effects of dispersal limitation and pond isolation, and therefore sources of phenotypic diversity, on local adaptation, and (3) whether the level of genetic diversity present in this system influences D. pulex’s interactions with other zooplankton species. The results have implications for understanding how communities respond to environmental change, and for integrating evolution into the process of community assembly.